Strategic Project - UI 62 - 2011-2012

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Organizational Unit

Publications

Phenolic profiling of portuguese propolis by LC–MS spectrometry: uncommon propolis rich in flavonoid glycosides

Publication . Falcão, Soraia; Vale, Nuno; Gomes, Paula; Domingues, Maria R.M.; Freire, Cristina; Cardoso, Susana M.; Vilas-Boas, Miguel

Propolis is a chemically complex resinous substance collected by honeybees (Apis mellifera) from tree buds, comprising plant exudates, secreted substances from bee metabolism, pollen and waxes. Its chemical composition depends strongly on the plant sources available around the beehive, which have a direct impact in the quality and bioactivity of the propolis. Being as Portugal is a country of botanical diversity, the phenolic characterisation of propolis from the different regions is a priority. Objective Extensive characterisation of the phenolic composition of Portuguese propolis from different continental regions and islands. Method Forty propolis ethanolic extracts were analysed extensively by liquid chromatography with diode-array detection coupled to electrospray ionisation tandem mass spectrometry (LC-DAD-ESI-MSn). Results Seventy-six polyphenols were detected in the samples and two groups of propolis were established: the common temperate propolis, which contained the typical poplar phenolic compounds such as flavonoids and their methylated/esterified forms, phenylpropanoid acids and their esters, and an uncommon propolis type with an unusual composition in quercetin and kaempferol glycosides - some of them never described in propolis. Conclusion The method allowed the establishment of the phenolic profile of Portuguese propolis from different geographical locations, and the possibility to use some phenolic compounds, such as kaempferol-dimethylether, as geographical markers. Data suggest that other botanical species in addition to poplar trees can be important sources of resins for Portuguese propolis. Copyright (c) 2012 John Wiley & Sons, Ltd.

2013Journal article

Restricted access

Phenolic constituents of lamium album: focus on isoscutellarein derivatives

Publication . Pereira, Olívia R.; Domingues, Maria R.M.; Silva, Artur; Cardoso, Susana M.

Lamium album L. is an edible plant which is consumed raw or cooked, in particular in the Mediterranean and surrounding areas. It is also consumed as tea infusions and as a main component of food supplements, because of its pharmacological effects. Despite being consumed by humans for centuries, the chemical composition of L album L is far from being understood. In this study, a purified ethanolic extract (PEEL) was prepared and further analyzed by high performance liquid chromatography and electrospray mass spectrometry. Overall, verbascoside accounted for approximately half of the phenolic content of the extract, but this also contained other bioactive phenolic compounds herein detected for the first time in the genus, namely isoscutellarein derivatives. The latter included isoscutellarein-7-O-allosyl(1 -> 2)glucoside, its O-methyl derivative, three acetyl derivatives of isoscutellarein-O-allosyl glucoside and one acetylated form of O-methylisoscutellarein-7-O-allosyl(1 -> 2)glucoside. From those, the main isoscutellarein derivative was assigned to isoscutellarein-7-O-(6-O-acetyl-beta-allosyl)(1 -> 2)-beta-glucoside, as confirmed by NMR. Altogether, isoscutellarein derivatives accounted for almost 30% of PEEL phenolics. Since verbascoside and isoscutellarein derivatives are main components of L album L ethanolic extract, their possible association to the health benefits of the plant is discussed.

2012Journal article

Open access

Mentha aquatica: source of flavanone glycosides

Publication . Pereira, Olívia R.; Domingues, Maria R.M.; Cardoso, Susana M.

Mentha aquatica L., commonly known as water mint, is a perennial herb that grows in Europe temperate regions. This plant is used in traditional medicine for the treatment of external inflammation, rheumatism, colds, respiratory problems and difficult menstruation [1]. It has been described as a good source of phenolic compounds with high scavenger activity [2]. In this study, a purified ethanolic extract of M. aquatica was prepared and its specific phenolic composition was determined. The extract of the aerial parts of M. aquatica was prepared according the procedure described by Pereira et al [3] and analyzed by high performance liquid chromatography with diode array detection with quantification of main phenolic compounds, using the external standard method. In order to determine the exact structure of phenolic compounds, the HPLC eluted fractions were manually collected and further analyzed by tandem electrospray mass spectrometry. The purified ethanolic extract of M. aquatica was mainly rich in flavanones comprises eriodictyol, hesperitin and naringenin glycosides. Moreover, the purified ethanolic extract of M. aquatica contained moderate amounts of rosmarinic acid, a phenolic acid very common in Mentha species and in Lamiaceae family.

2012Conference object

Open access